Effects Of Metabolizable Energy Research Articles

Effect of metabolizable energy and crude protein levels on performance, fertility, hatchability and egg quality of Rajasri breeder birds

This study investigated the impact of different levels of dietary energy and crude protein on productive performance, egg quality, and reproductive parameters in Rajasri breeder birds during a 12-week period between 25 to 36 weeks of age. A total of 648 birds were divided into nine dietary treatments, each with eight replicates, following a 3 × 3 factorial arrangement of three dietary metabolizable energy levels (2400, 2500, and 2600 kcal ME/kg) and three crude protein levels (14, 15, and 16%). The results of the study indicated that metabolizable energy had a significant effect on feed intake, egg weight, body weight, yolk colour, and shell thickness. However, there was no significant effect of energy on egg production and feed efficiency. An increase in egg weight was observed as crude protein levels increased in the diet, but there was no significant difference in albumin quality, yolk index, and shape index. Yolk colour was higher in the 2600 kcal ME/kg fed group. Furthermore, the study found that there was no significant effect of ME and CP levels on the percentage of shell, but shell thickness decreased as energy increased. There was also no significant effect on density and shell breaking strength, fertility, hatchability on total eggs set (TES), and hatchability on fertile eggs set (FES). Based on the findings, concluded that the Rajasri breeder birds require a diet containing 2400 kcal ME/kg and 14% CP for optimal productive and reproductive performance.

Chicken adaptive response to nutrient density: immune function change revealed by transcriptomic analysis of spleen.

Feed accounts for the largest portion (65-70%) of poultry production costs. The feed formulation is generally improved to efficiently meet the nutritional needs of chickens by reducing the proportion of crude protein (CP) and metabolizable energy (ME) levels in the diet. Although many studies have investigated the production performance during dietary restriction, there is a lack of research on the mechanisms by which immune cell function is altered. This study examined the effects of ME and CP restriction in the chicken diet on serum immunoglobulins and expression of immune function genes in spleen. Changes in serum immunoglobulins and immune-related gene expression were analyzed in 216 YS-909 broilers fed with 9 different dietary treatments, including experimental treatment diets containing low, standard, and high levels of ME or CP in the diet. At 42 days of age, serum immunoglobulins and expression of spleen immune genes in 6 female chickens selected randomly from each dietary treatment (3×3 factorial arrangement) group were measured by enzyme-linked immunosorbent assay (ELISA) and transcriptomic analysis using RNA sequencing, respectively. The results showed that the IgM level in the low ME group chickens was significantly (p < 0.05) lower than that in other groups. In addition, immune-related genes, such as MX1, USP18, TLR4, IFNG and IL18 were significantly upregulated when the dietary nutrient density was reduced, which may put the body in an inflammatory state. This study provided general information on the molecular mechanism of the spleen immune response to variable nutrient density.

Effect of Metabolizable Energy and Crumble Quality of the Diet on Growth Performance of Broilers

In order to optimize the growth performance of broilers, diets are formulated to a recommended ME concentration. In addition, broilers (chicks) are often fed diets in the form of crumbles in early production to improve growth performance. Thus, the objective of this study was to determine the effect of ME concentration in diets and if removal of crumble fines influenced the growth performance response of broilers. At hatch, a total of 300 one-day-old male broilers (Cobb 500, initial BW 0.093 lb) were used in an 18-day study. Broilers were housed in 3 Petersime batteries with ad libitum access to feed and water. Treatments were randomly assigned to 60 cages balanced by location, resulting in 10 cages per treatment with 5 broilers per cage. Treatments were arranged in a 2 × 3 factorial of ME content (1,376 and 1,346 ME, kcal/lb) and crumbled diets with or without fines (removed particles < 1,532 µm or < 864 µm). Crumble treatments were fed with no sifting (NS) or sifted using either a screen with 0.06-in. openings (removed particles < 1,532 µm) or a screen with 0.03-in. openings (removed particles < 864 µm). Data were analyzed as a completely randomized design using the GLIMMIX procedure of SAS (v. 9.4, SAS Institute, Inc., Cary, NC). There was no evidence of an interaction between crumble fines removal and ME or main effect of ME. Body weight gain (BWG) and total feed intake (TFI) increased (P < 0.05) when broilers were fed crumbles sifted with a 0.06-in. screen compared to NS and crumbles sifted with a 0.03-in. screen. Broiler feed conversion ratio (FCR) improved (P < 0.001) when broilers were fed crumbles sifted with a 0.06-in. screen compared to those fed NS and sifted with a 0.03-in. screen. In conclusion, broilers fed crumbles with particles < 1,532 µm removed had an improved FCR and an increased BWG and TFI regardless of the ME content of the diet. Increasing ME from 1,346 to 1,376 kcal/lb did not influence growth performance of broilers from d 0 to 18 d of age.

280 Effects of metabolizable energy and standardized ileal digestible lysine levels on lactating sow and litter performance

Abstract The objective was to determine the effects of metabolizable energy (ME) and standardized ileal digestible (SID) lysine (Lys) levels on lactating sows and litter performance. A total of 600 sows (Camborough; PIC, Hendersonville, TN) were blocked by parity (P1, P2, P3+) on d 112 of gestation and allotted to 1 of 6 treatments arranged in a 2 x 3 factorial with the main effect of ME (3.2 and 3.4 Mcal/kg) and SID Lys (0.70, 0.85, and 1.00 %). Corn-soybean meal-based diets were fed from farrowing until weaning (d 21±2.3). Litters were cross-fostered until 48-h after farrowing to equalize litter size. Sows were weighed at d 112 of gestation and at weaning. Litter size and weight were collected at 24-h post-farrow and weaning. Daily feed intake was recorded from 48-h post-farrow until weaning. Data were analyzed using the GLIMMIX procedure of SAS with sow as the experimental unit. There was no evidence of interaction between ME and SID Lys for any response criteria. There was no evidence for an ME effect on sow performance. There was a quadratic effect (P&amp;lt; 0.05) of SID Lys on sow average daily feed intake, with the greatest intake at 0.85% SID Lys. Increasing SID Lys levels increased sow BW change (linear, P&amp;lt; 0.05). Litters from sows fed 3.4 Mcal of ME/kg had greater (P&amp;lt; 0.05) daily gain compared to those from sows fed 3.2 Mcal of ME/kg. Increasing SID Lys levels increased (linear, P&amp;lt; 0.05) litter weight at weaning and piglet daily gain. Wean-to-estrus interval, percentage of sows bred after weaning, total born on the subsequent parity, litter size at weaning, and percent of piglet removals were not influenced by dietary treatments. In summary, increasing ME levels did not affect sow performance, but improved litter and piglet daily gain. Increasing SID Lys levels improved both litter and sow performance.

Metabolizable energy levels in diets with high lysine for growing and finishing pigs

The objective of this experiment was to evaluate the effects of metabolizable energy (ME) levels in diets with high digestible lysine concentration on performance, carcass traits, and meat quality of barrows from 95 to 158 days of age. Eighty commercial hybrid barrows (50 ± 1.82 kg) selected for lean meat deposition, were assigned to four dietary treatments (3,150, 3,235, 3,320, and 3,400 kcal EM kg-1) in a randomized design with 10 replicate pens per treatment and two pigs per pen. From 95 to 116 days of age, we observed no effects of ME on final body weight (FBW), average daily gain (ADG), metabolizable energy intake (MEI), and feed conversion (F: G). Average daily feed intake (ADFI) decreased linearly with increasing ME levels (? = 5.79961 - 0.00096790X - r2 = 0.89). From 95 to 137 days of age, no effects of ME were observed on final body weight (FBW), average daily gain (ADG), metabolizable energy intake (MEI), and feed conversion (F: G). Average daily feed intake (ADFI) decreased linearly with increasing ME (?= 6.1176 - 0.001X - r2= 0.97). From 95 to 158 days, of age no effects of ME were observed on FBW and ADG. Dietary ME influenced the ADFI and F: G, which decreased linearly with increasing ME concentrations (?= 8.12951 - 0.00149X - r2= 0.99; ?= 6.0914 - 0.001X - r² = 0.75, respectively). There was a linear increase in loin eye area (LEA) with increasing ME (? = - 29.851 + 0.0207 X - r² = 0.87). Backfat thickness, pH, and temperature, measured at different times after slaughter (0 min, 45 min, 3 h, and 24 h), were not affected by dietary ME. The level of ME also did not affect the meat quality parameters Color L*, Color a*, Color b*, Warner-Bratzler shear force, thaw water losses, cooking water losses, sum of water losses, intramuscular fat content, and TBARS. Diets with 3,400 kcal kg-1 ME, corresponding to 2.75, 2.57, and 2.31 g digestible lysine/Mcal of ME for pigs from 95 to 116, 116 to 137, and 95 to 158 days of age, respectively, resulted in best performance and carcass traits, without negative effects on meat quality.

Increasing metabolisable energy and protein supplementation to stimulate the subsequent milk production during late gestation by increasing proliferation and reducing apoptosis in goat mammary gland prepartum

In total, 32 pregnant goats were assigned randomly to four diets fed from Day 100 of pregnancy to Day 30 after parturition, to determine the effects of metabolisable energy (ME) and metabolisable protein (MP) supplementation levels on feed intake, subsequent colostrum and milk production and expression of genes regulating mammary-cell proliferation and apoptosis. Diets were as follows: (1) diet with ME and MP provided according to NRC recommendations (control), (2) diet with extra 10% ME, (3) diet with extra 10% MP, and (4) diet 1 with 10% extra of both ME and MP. Mammary biopsies were obtained from each udder half 24 h after parturition. Feed intake (g/day), and colostrum (kg/day) and milk (kg/month) production increased when the extra ME and MP were provided together prepartum and in early lactation (P &amp;lt; 0.05). Relative mRNA expressions significantly increased in the mammary gland of insulin-like growth factor 1 (IGF-1, 4.3-fold), IGF-1 receptor (IGF-1R, 3.6-fold) and B-cell lymphoma 2 (Bcl-2, 4.6-fold), whereas insulin-like growth factor binding protein 3 (IGFBP-3, 3.2-fold), Bcl-2-associated X protein (Bax, 16.7-fold) and the ratio of Bax:Bcl-2 expressions significantly decreased (69.8-fold) with increased ME and MP levels fed in late gestation. In conclusion, colostrum production and milk yield in the early lactation period are sensitive to nutrient supply during gestation, where increased dietary ME as well as MP supplementation levels during late gestation will favour mammary development, by increasing expression of genes stimulating cellular proliferation (IGF-1, IGF-1R, Bcl-2) and reduced those stimulating apoptosis (IGFBP-3, Bax).

0951 Effect of metabolizable energy and sulfur amino acid levels on productive performance and economic return of laying hens

0951 Effect of metabolizable energy and sulfur amino acid levels on productive performance and economic return of laying hens

Effects of metabolizable energy and crude protein levels on laying performance, egg quality and serum biochemical indices of Fengda-1 layers.

This study was conducted to investigate the effects of dietary ME and CP levels on laying performance, egg quality and serum biochemical indices of Fengda-1 layers. In a 2 × 3 factorial arrangement, 2,400 Fengda-1 layers (32 wk of age) were randomly assigned to 6 experimental diets with 2,650 and 2,750 kcal of ME/kg of diet, each containing 14.50%, 15.00% and 15.50% CP, respectively. Each dietary treatment was replicated 5 times, and feed and water were provided ad libitum. The trial lasted for 10 wk, including a 2-week acclimation period and an 8-week experimental period. Our results showed that ADFI decreased as the ME level of diet increased from 2,650 to 2,750 kcal/kg (P < 0.05). Layers fed diets with 2,750 kcal/kg ME exhibited higher mortality than those fed with 2,650 kcal/kg ME (P < 0.05). Birds fed with 14.50% and 15.00% CP had higher egg production (EP) and egg mass (EM) than those fed with 15.50% CP (P < 0.05). Yolk color increased as the ME level of the diet increased from 2,650 to 2,750 kcal/kg, however, the eggshell thickness decreased (P < 0.05). Serum concentrations of uric acid and triglyceride in layers fed diets with 2,750 kcal/kg ME were higher than those fed diets with 2,650 kcal/kg ME (P < 0.05). There was no significant interaction between ME and CP on laying performance, egg quality, or serum biochemical indices (P > 0.05). Based on the data under the experimental conditions, the optimal dietary ME and CP levels of Fengda-1 layers are 2,650 kcal/kg and 15.00% (33 to 41 wk of age).

Effects of metabolizable energy and balanced protein on egg production, quality, and components of Lohmann Brown laying hens

SUMMARY A 4 × 3 factorial experiment with 4 dietary ME levels (2,400, 2,550, 2,700, and 2,850 kcal/ kg) and 3 CP levels (14.5, 16.0, and 17.5%) was conducted to determine the effects of ME and CP on egg production (EP) performance, egg quality, and egg components of laying hens. The protein ingredients were composed of soybean meal (36.5%), cottonseed meal (36.5%), and canola meal (27.0%). A total of 900 commercial Lohmann Brown pullets, 26 wk of age, were randomly assigned into 12 treatments (5 replicates with 15 birds per replicate). Feed and water were provided ad libitum throughout the experiment (12 wk). The optimum intake of ME and CP for maximum egg production, egg mass (EM), and feed conversion ratio (FCR) was calculated. There was an interaction between ME and CP on EP, EM, and FCR (P < 0.001). By response surface analysis, the ranges of estimated optimum ME and CP intake were 325.7 to 331.7 kcal/d (2,591 to 2,683 kcal/kg) and 19.5 to 20.7 g/d (15.58 to 16.64%), respectively, for optimum EP, EM, and FCR. The highest EP and EM were observed with 16% CP (21.13 g/d) and 2,400 kcal/kg of ME (316.95 kcal/d) in the diet. Diets with high CP (17.5%) and low energy (2,400 kcal/kg) exhibited the poorest EP (71.58%), EM (42.15 g/d), egg shell quality (0.289 mm), and broken egg ratio (0.25%). Thus, moderate ME and high balanced protein are very important for optimizing the FCR, EP, and EM of Lohmann Brown laying hens.

Desempenho, carcaça e cortes de frangos caipira Francês Barré (Gris Barré Cou Plumé)

This study aimed to analyze the effects of metabolizable energy levels and the age at slaughter on growth performance, carcass yield and cuts broilers Caipira French Barre. The experiment was conducted in Parauapebas, PA. We used 192 one day chicks reared in intensive system. The experimental design was completely randomized with three treatments. Each treatment consisted of four replications, the experimental unit being a box of 16 birds. The treatments were defined according to the levels of metabolizable energy diets (1 to 28 days) and late (29 to 90 days), respectively: T1 - 3000 and 3100 kcal of ME/kg, T2 - 3100 and 3200 kcal/kg, T3 - 3200 and 3300 kcal of ME/kg. The variables studied were initial weight, final weight, feed intake and feed conversion, protein consumed, metabolized protein consumed, energy efficiency and protein efficiency. The characteristics of carcasses of birds, analyzed with 77, 84 and 91 days of age were the carcass, breast, thigh, drumstick, wing, back, wings, feet, head and neck. The statistical analysis was performed using the ANOVA procedure for a completely randomized model with the System for statistical analysis and genetics (SAEG, 2007). Differences between means of variables were performed by Tukey's test at a level of 5%. The energy levels in the diets did not affect on the performance and carcass yield, breast, thighs, drumsticks, wings, feet and head + neck in birds. The level of 3200 kcal/kg provided better yield back. The protein and metabolic energy consumed by the birds improved with higher energy content of feed during the fattening stage. Age at slaughter did not affect carcass yield, however the birds slaughtered at 90 days of age showed higher breast yield.

Effect of feeding different levels of energy and protein on performance of Aseel breed of chicken during juvenile phase

A study was conducted to evaluate the effect of feeding different metabolizable energy (ME) and crude protein (CP) levels on performance of Aseel chicken during 0 to 8 weeks of age (Juvenile phase). At 1 day old, 432 chicks were randomly distributed into nine groups. Each group had 48 chicks distributed into eight replicates with six birds in each. Maize-soybean meal-based diets with three ME levels (2,400, 2,600 and 2,800 kcal/kg) and three CP levels (16%, 18% and 20%) were fed to birds in a 3 × 3 factorial design. Different ME levels had significant effect on body weight gain (BWG), feed intake and feed conversion ratio (FCR). Birds fed diet with 2,400 kcal/kg ME had significantly lower BWG (P < 0.004), lower shank length (P < 0.0007), higher feed intake (P < 0.0001) and poor FCR (P < 0.0001) than those fed diet with either 2,600 or 2,800 kcal/kg ME. Energy efficiency ratio was not influenced by ME, CP or their interaction. However, protein efficiency ratio was significantly higher at higher ME levels and lower at higher CP levels. There was significant effect of ME, CP and their interaction on serum protein and cholesterol levels. However, they made no significant effect on antibody titre against New Castle disease vaccine. The study concluded that provision of 2,600 kcal/kg ME and 16% CP would be ideal for optimum growth of Aseel birds during juvenile phase. However, to obtain better FCR, feeding Aseel birds with diet having 2,800 kcal/kg ME and 16% CP would be ideal.

Energy and amino acid content in phase 1 nursery diet: piglet performance and body chemical composition

It was evaluated the effects of metabolizable energy (ME) and digestible lysine (dLYS) densities on performance and body composition of weaned piglets. The study used 114 piglets weaned at 7.4 ± 0.80 kg, out of which 108 were allotted in the nursery and 6 were slaughtered on the weaning day to determine comparative data of body chemical composition. Six nutrients densities were stipulated from a previous study based on the highest nitrogen retention, maintaining the following ME:LYS relationship in the experimental diets: 3,390:1.291; 3,450:1.409; 3,650:1.411; 3,780:1.461; 3,940:1.507; and 4,109 kcal/kg ME:1.564% dLYS. The experimental diets were offered for 13 days when the piglets reached 12.986 ± 1.449 kg of body weight. The probable residual effects of nutritional density on the subsequent performance of the piglets were evaluated. At the end of initial phase 1, six piglets from each density were slaughtered to determine their chemical composition in body fractions and empty body. There was no significant influence of nutritional levels on the performance of the piglets at the end of the evaluation. The results of food conversion and body composition confirm the level indicated in the previous study, 4 g dLYS/Mcal of ME. The increase of energy and lysine densities confirms the need for a correct relationship among both of them to assure better performance of the piglets at the beginning of the growing phase.

Effects of dietary energy intake and cold exposure on kinetics of plasma phenylalanine, tyrosine and protein synthesis in sheep

An isotope dilution method of [2H5]phenylalanine (Phe) and [2H2]tyrosine (Tyr) was used to determine the effects of metabolisable energy (ME) intake and cold exposure on plasma Phe and Tyr turnover rates in sheep. Whole body protein synthesis (WBPS) was calculated with the [2H5]Phe model. Eight adult sheep were assigned to two dietary treatments receiving the same amount of crude protein and either 515 or 828 kJ · kg BW−0.75 · d−1 of ME (Me-ME diet and Hi-ME diet, respectively) with a crossover design for two 28 d periods. The sheep were exposed from a thermoneutral environment (23 ± 1°C) to a cold environment (2 ± 1 to 4 ± 1°C) for 6 d for each dietary treatment. The primed-continuous infusion method of isotope dilution was conducted in both environmental temperatures. Plasma Phe turnover rate (PheTR) tended to be greater and plasma Tyr turnover rate (TyrTR) was greater (p = 0.03) for the Hi-ME diet compared with the Me-ME diet. Plasma PheTR increased (p = 0.04) and plasma TyrTR tended to increase during cold exposure. Whole body protein synthesis tended to be greater for the Hi-ME diet compared with the Me-ME diet and increased (p = 0.03) during cold exposure compared to the thermoneutral environment, but no interaction was detected. It was concluded that in sheep, plasma PheTR and WBPS (as determined by the [2H5]Phe model) tended to be influenced by and plasma TyrTR was influenced by ME intake. Further, plasma PheTR and WBPS increased and plasma TyrTR tended to increase during cold exposure.

Response of broilers to practical diets with different metabolizable energy and balanced protein concentrations

Experiment was conducted to study the effect of Metabolizable Energy (ME) and Balanced Protein (BP) on the performance of 1- to 35-day-old male and female Hubbard x Hubbard broilers. Set in a factorial arrangement, dietary treatments involved 3 levels of ME (2650, 2750, or 2850 kcal per kg diet) and 4 levels of Balanced Protein (expressed as 8.4, 9.0, 9.6, or 10.2 g Standardized Ileal Digestible lysine per kg). Each diet was fed to 5 replicate pens of 17 chicks. Dietary ME and BP did not interact for any of the parameters studied (p>0.05). The main effect of ME was significant (p<0.05) for feed intake, body weight, and feed conversion ratio at all ages. Highest ME (2850 kcal) resulted in 35 day feed intake and feed conversion ratio that was significantly (p<0.05) low compared with those fed on lower levels of ME; while 35 day body weight was significantly (p<0.05) high at 2850 kcal compared with 2650 kcal ME. Feed intake and body weight improved linearly (p<0.05) with increasing BP from 8.4 to 10.2 g per kg, while the BP did not have any effect on feed conversion ratio. Dietary combinations of ME and BP to optimize body weight and feed conversion ratio are suggested on weekly basis.

사료의 ME가와 단백질 수준이 백세미의 생산성과 경제성에 미치는 영향

An experiment was conducted to investigate the effect of ME and crude protein (CP) content of diet on the performance and production cost of white semibroiler chickens. Three hundred sixty hatched white semibroiler chickens (Hy-Line male) were assigned to low dietary treatments of different metabolizable energy (ME) value and crude protein (CP) content: T1; ME 3,040 and 3,070 kcal/kg, CP 21.40 and 20.86%, T2; ME 2,950 and 3,000 kcal/kg, CP 20.62 and 19.70%, T3; ME 2,950 and 3,000 kcal/kg, CP 19.90 and 18.70% and T4; ME 2,900 and 2,920 kcal/kg, CP 18.50 and 18.00% for starter diet ( wk) and power diet ( wk), respectively There were significant (P

Effects of Metabolizable Energy and Amino Acid Levels on Turkey Performance from Hatch to Marketing

Two experiments were conducted with growing turkeys from hatch to market examining the performance at various dietary energy and amino acid (AA) levels as well as the relationship between energy and essential amino acids at these energy levels. The results of the first experiment indicated that increasing ME alone improved feed efficiency (FE); however, it did not affect BW in either toms or hens. In addition, increasing ME alone resulted in better regulation of caloric intake (CI) in toms than in hens. The caloric efficiency (CE) (BW/CI) improved with the higherenergy diets. In a second experiment both AA and ME levels were changed. Using 95% of NRC amino acid levels depressed performance, whereas turkeys receiving 105 and 110% of the recommended AA levels had improved BW and FE until 6 wk. From 7 to 19 wk, increasing dietary AA levels decreased feed intake (FI). Increasing both AA and ME together did not, in all cases, produce the same effect as altering their levels independently.

The effect of body weight on the upper limit to protein deposition in a defined population of growing gilts.

In a stress-free environment and given adequate intakes of essential nutrients, protein deposition (PD) in growing pigs is determined by either energy intake or the genetically determined upper limit to body protein deposition (PDmax). In this experiment, the effect of metabolizable energy (ME) intake on PD was determined in 24 female pigs between 25 and 70 kg BW. Casein and cornstarch-based diets that were not limiting in any of the essential nutrients were offered semi-ad libitum (12 pigs) or restrictively at 1.8, 2.2, or 2.6 times the ME requirements for maintenance (MEm; four pigs at each level of ME intake). Nitrogen balances were determined over 7-d periods at approximately 25, 40, and 70 kg BW. The serial slaughter method was used to determine average PD over the entire BW range. Based on the N balances, PD increased up to intakes of 22.6, 21.3, and 25.1 MJ ME/d at 25, 40, and 70 kg BW, respectively. At higher ME intakes, PDmax was at least 156 g/d at 25 kg body weight; it was 149 g/d at 40 and 150 g/d at 70 kg BW. The serial slaughter technique showed a PDmax of 127 g/d at ME intakes above 22.5 MJ/d. At 25 kg BW, intakes of ME of approximately four times MEm are necessary to achieve PDmax. The results indicate that PDmax at 25 kg BW is at least as high as at 40 and 70 kg BW.

Independent Effects of Dietary Metabolizable Energy and Protein Concentrations on Performance and Carcass Characteristics of Tom Turkeys

An experiment was conducted to determine the independent and interaction effects of dietary metabolizable energy (ME) and protein concentrations on performance of Large White toms from 9 to 20 weeks of age. Diet treatments consisted of a complete factorial arrangement of three ME concentrations and three protein concentrations within each age interval (9 to 12, 12 to 16, and 16 to 20 weeks). The different ME concentrations were obtained by using an animal-vegetable fat blend at 0, 4, or 8% of the diets. Dietary protein levels tested provided approximately 88, 97, or 107% of those recommended by National Research Council (1977) for each age interval. The ME concentrations represented 95, 100, or 105% of those used most frequently in commercial feeding programs in the central United States.Dietary ME and protein concentrations had significant (P<.03) independent effects on turkey performance. As each diet variable was increased, gain in body weight and feed efficiency were improved. Increasing dietary ME reduced the amount of protein consumed per kilogram of gain but not the ME consumed per kilogram of gain. Protein consumed per kilogram gain increased as dietary protein increased, while ME intake per kilogram gain decreased. Carcass composition and parts yield of the carcass were affected only slightly by dietary ME and protein concentration. No significant (P>.10) interaction effects of dietary ME and protein were detected, except in the instance of absolute quantity of carcass protein (P<.07). Data from this experiment and results of other research suggest that the use of “optimum ME-to-protein ratios” as a restriction in formulation of turkey diets may be inappropriate and that greater emphasis should be placed on the nutritional and economic implications of the independent effects of ME and protein on rate of growth and feed efficiency.

Rapid determination of metabolisable energy of foods using cockerels

1. Adult cockerels were trained to consume their daily food allowance of about 100 g in 1 h. Excreta were collected for the next 24 h and the metabolisable energy (ME) content of the diet was determined. 2. Two different diets were used to study effects of ME on adaptation to diet. Repeatable estimates of ME were obtained without a period of adaptation. 3. No difference in ME was found when a test diet was fed to adult cockerels for 1 h, or fed continuously and excreta collected over 5 d. The conventional total collection method of determining ME using groups of growing chickens yielded similar results. 4. Excreta collected between 24 and 48, or 48 and 72 h post‐feeding yielded constant energy values following feeding of two different diets, indicating that all excreta from the 1‐h feeding were voided during the next 24 h. 5. The method is precise and results can be reported 36 h after receipt of food sample.